The article “Membraneless water filtration using CO2” by Shin et al. (Nature Communications 8:15181), 2 May 2017, hereby incorporated by reference herein, describes a continuous flow particle filtration device in which a colloidal suspension flows through a straight channel in a gas permeable material made of polydimethylsiloxane (PDMS). A CO2 gas channel passes parallel to the wall and dissolves into the flow stream. An air channel on the other side of the wall prevents saturation of CO2 in the suspension and the resulting gradient of CO2 causes particles to concentrate on sides of the channel, with negatively charged particles moving toward the air channel and positively charged particles toward the CO2 channel. The water away from the sides of the channel can be collected as filtered water.
The article “Diffusiophoresis at the macroscale” by Mauger et al. (arXiv: 1512.05005v4), 6 Jul. 2016, hereby incorporated by reference herein, discloses that solute concentration gradients caused by salts such as LiCl impact colloidal transport at lengthscales ranging roughly from the centimeter down to the smallest scales resolved by the article. Particles of a diameter of 200 nm were examined.
The article “Origins of concentration gradients for diffusiophoresis” by Velegol et al, (10.1039/c6sm00052e), pages 4686 to 4703, 13 May 2016, hereby incorporated by reference herein, describes diffusiophoresis possibly occurring in georeservoir extractions, physiological systems, drying operations, laboratory and industrial separations, crystallization operations, membrane processes, and many other situations, often without being recognized.
PCT Publication WO 2015/077674 discloses a process that places a microparticle including a salt in proximity to a membrane such that the microparticle creates a gradient generated spontaneous electric field or a gradient generated spontaneous chemiphoretic field in the solvent proximal to the membrane. This gradient actively draws charged particles, via diffusiophoresis, away from the membrane thereby removing charged particulate matter away from the membrane or preventing its deposition.